Air Ambulance Leaps into Air: Misrigged Flying Controls (Air Evac Lifeteam EC130T2 N894GT, Memphis, TN)
On 28 January 2018 air ambulance Airbus Helicopters EC130T2 N894GT of Air Evac Lifeteam was damaged in a hard landing after it inadvertently became airborne while on the elevated landing site at Memphis Regional Medical Center in Tennessee. None of the 4 occupants were injured but impact was hard enough to spread the skids, caused minor structural damage and set off the Emergency Locator Transmitter (ELT).
The 58 year old pilot pilot had 6267 hours total time, but only 9 on type. having completed a 5 day EC130 course at Airbus in early November 2017. His last proficiency check was 11 days earlier. According to the NTSB:
While on a long final approach to the heliport, there was a left crosswind present and he had to reduce collective pitch control friction three times in order to move the collective as fast as he felt he needed to. He brought the helicopter to a hover as he reached the heliport, then turned the helicopter to the right and landed.
After landing, he started the after-landing portion of the checklist, then turned the throttle twist grip on the collective from “FLY to “IDLE,” believing [our emphasis] that he had engaged the collective lock.
He then turned the horn mute switch to mute, grabbed the cyclic pitch control with his left hand, and reached for the clock start button with his right hand.
As he was reaching for the clock button, the collective “popped up,” and the helicopter became airborne. He immediately grabbed the cyclic with his right hand, the collective with his left hand, and twisted the twist grip to “FLY.” The helicopter then landed hard, and the emergency locator transmitter (ELT) activated. After exiting the helicopter, the flight nurse advised the pilot that there was damage to the sheet metal of the helicopter.
CCTV footage showed the occurrence:
The Safety Investigation
Examination of the helicopter revealed minor damage. The skid type landing gear was spread out, and both landing gear cross tubes were deformed. The forward belly panels were dented from contact with the forward landing gear cross tube, and the aft closeout panels were dented from contact with the aft landing gear cross tube.
Investigators had access to engine data from the Safran Arriel 2D engine’s full authority digital engine control (FADEC) system stored on an engine data recorder (EDR). The helicopter was also equipped with an Appareo Vision 1000 unit, which records images, audio and limited flight data onto a removable SD memory card. NTSB comment that:
Review of the onboard video depicted a series of events consistent with the pilot’s statement.
Review of EDR data indicated that, during the incident portion of the flight, the recorded transducer position for the collective showed the collective rising from an unlocked position with the helicopter’s engine transitioning from “Idle” to “Flight.”
The EC130 can be converted between a dual-pilot configuration (e.g. for training) to a single-pilot configuration. Two days earlier, a mechanic at the Air Evac base at Jackson, Tennessee had removed the right seat dual controls to reconfigured the helicopter for single-pilot operation. When an FAA inspector examined the aircraft…
The collective was placed in the full-down position to attach a spring scale to the twist grip to measure the force required to pull it through its upward travel; however, once the mechanic removed his hand from the collective prior to attaching the spring scale; the collective immediately climbed unassisted to approximately the mid-travel position, indicating that the collective was improperly balanced for the single-pilot configuration. It was determined that the spring force was much greater (approximately twice that required) than it should have been in the upward direction.
The maintenance manual describes the process for “Adjustment – Collective Stick Balance” (extracts are within the Public Docket). The implication of this investigation finding is that the rebalancing was either not conducted when the dual controls were removed or that it was not completed successfully.
The operator has changed their abbreviated checklist for the EC130T2, so that the first item after landing is to roll the twist grip to “IDLE” and then place and confirm the collective pitch is “Down/locked.” A “NOTE” has been added to
“Visually and verbally confirm collective is locked.”
UPDATE 3 March 2022: NTSB Probable Cause
The pilot’s failure to lock the collective pitch control after landing, and the mechanic’s failure to properly balance the collective pitch control after converting the helicopter to a single-pilot configuration, which resulted in an uncommanded collective movement and subsequent hard landing.
- Air Ambulance Helicopter Struck Ground During Go-Around after NVIS Inadvertent IMC Entry
- A HEMS Helicopter Had a Lucky Escape During a NVIS Approach to its Home Base
- NVIS Autorotation Training Hard Landing: Changed Albedo
- Low Recce of HEMS Landing Site Skipped – Rotor Blade Strikes Cable Cutter at Small, Sloped Site
- NTSB on LA A109S Rooftop Hospital Helipad Landing Accident
- Pedestrian Seriously Injured by Air Ambulance Landing at Melbourne Hospital
- Air Ambulance B407 Hospital Helipad Deck Edge Tail Strike During Shallow Approach
- Grand Canyon Air Tour Tragic Tailwind Landing Accident
- EC130 Door Loss Damaged Main Rotor Blades
- Hawaiian Air Tour EC130T2 Hard Landing after Power Loss (Part 1)
- Hawaiian Air Tour EC130T2 Hard Landing after Power Loss (Part 2 – Survivability)
- Loose Engine B-Nut Triggers Fatal Forced Landing
- Loose B-Nut: Accident During EC130B4 Maintenance Check Flight
- EC130B4 Destroyed After Ice Ingestion – Engine Intake Left Uncovered
- US Fatal Night HEMS Accident: Self-Induced Pressure & Inadequate Oversight
- Air Methods AS350B3 Air Ambulance Tucson Tail Strike
- US HEMS EC135P1 Dual Engine Failure: 7 July 2018
- Misassembled Anti-Torque Pedals Cause EC135 Accident
- Why a Collective Control Came Loose in a Pilot’s Hand…
- B1900D Emergency Landing: Maintenance Standards & Practices
- Fiery Fatal AW119 Accident in Russia After Loss of Tail Rotor Control
- BEA Point to Inadequate Maintenance Data and Possible Non-Conforming Fasteners in ATR 42 Door Loss
- The Curious Case of the Missing Shear Pin that Didn’t Shear: A Fatal Powerline Stringing Accident
- Emergency S-76D Landing Due to Fumes
- Fatal $16 Million Maintenance Errors
- Ungreased Japanese AS332L Tail Rotor Fatally Failed
- SAR AS365N3 Flying Control Disconnect: BFU Investigation
- In-Flight Flying Control Failure: Indonesian Sikorsky S-76C+ PK-FUP
- Maintenance Issues in Fire-Fighting S-61A Accident
- Hoist Assembly Errors: SAR Personnel Dropped Into Sea
- ATR 72 Rudder Travel Limitation Unit Incident: Latent Potential for Misassembly Meets Commercial Pressure
- UPDATE 9 April 2022: SAR Seat Slip Smash (RCAF CH149 Leonardo Cormorant LOC-I)
You might also find these safety / human factors resources of use:
- James Reason’s 12 Principles of Error Management
- Back to the Future: Error Management
- Aircraft Maintenance: Going for Gold?
- Critical Maintenance Tasks: EASA Part-M & -145 Change
- This 2006 review of the book Resilience Engineering by Hollnagel, Woods and Leveson, presented to the RAeS by Aerossurance’s Andy Evans: Resilience Engineering - A Review and this book review of Dekker’s The Field Guide to Understanding Human Error: The Field Guide to Understanding Human Error – A Review.
Aerossurance worked with the Flight Safety Foundation (FSF) to create a Maintenance Observation Program (MOP) requirement for their contractible BARSOHO offshore helicopter Safety Performance Requirements to help learning about routine maintenance and then to initiate safety improvements.